- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Communication Compact CRLH Leaky-wave Antenna using TE20 Mode Substrate Integrated Waveguide for Broad Space Radiation Coverage
摘要： This paper introduces a combinational modulation method to be used in classic full-bridge single phase inverters. The proposed method eliminates even-order harmonics at the pulse width modulation (PWM) stage in the control section, unlike the conventional method of even order harmonic cancelation in the power stage, and offers a cost-effective design by switching one leg at high frequency. Using a low-cost digital signal controller platform, a regular sampling technique based on real-time calculation was employed to verify the feasibility of the proposed method on a 500-W single phase voltage source inverter. Performance characteristics, such as switching losses and harmonic distortions, are presented for the new approach and compared with a classic inverter modulation method.
关键词： switching frequency,Combinational logic circuits,inverters,pulse width modulation (PWM),silicon carbide,harmonic distortion
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE Transportation Electrification Conference and Expo, Asia-Pacific (ITEC Asia-Pacific) - Seogwipo-si, Korea (South) (2019.5.8-2019.5.10)] 2019 IEEE Transportation Electrification Conference and Expo, Asia-Pacific (ITEC Asia-Pacific) - Optimal scheduling of critical peak pricing considering photovoltaic generation and electric vehicle load
摘要： For long-wavelength space-based radars, such as the P-band radar on the recently selected European Space Agency BIOMASS mission, system distortions (crosstalk and channel imbalance), Faraday rotation, and system noise all combine to degrade the measurements. A first-order analysis of these effects on the measurements of the polarimetric scattering matrix is used to derive differentiable expressions for the errors in the polarimetric backscattering coefficients in the presence of Faraday rotation. Both the amplitudes and phases of the distortion terms are shown to be important in determining the errors and their maximum values. Exact simulations confirm the accuracy and predictions of the first-order analysis. Under an assumed power-law relation between σhv and the biomass, the system distortions and noise are converted into biomass estimation errors, and it is shown that the magnitude of the deviation of the channel imbalance from unity must be 4–5 dB less than the crosstalk, or it will dominate the error in the biomass. For uncalibrated data and midrange values of biomass, the crosstalk must be less than ?24 dB if the maximum possible error in the biomass is to be within 20% of its true value. A less stringent condition applies if the amplitudes and phases of the distortion terms are considered random since errors near the maximum possible are very unlikely. For lower values of the biomass, the noise becomes increasingly important because the σhv signal-to-noise ratio is smaller.
关键词： Biomass,Faraday rotation,polarimetric measurements,system distortion,calibration,long-wavelength radar
更新于2025-09-23 15:19:57
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Modal Analysis of 2-D Material-based Plasmonic Waveguides by Mixed Spectral Element Method with Equivalent Boundary Condition
摘要： For long-wavelength space-based radars, such as the P-band radar on the recently selected European Space Agency BIOMASS mission, system distortions (crosstalk and channel imbalance), Faraday rotation, and system noise all combine to degrade the measurements. A first-order analysis of these effects on the measurements of the polarimetric scattering matrix is used to derive differentiable expressions for the errors in the polarimetric backscattering coefficients in the presence of Faraday rotation. Both the amplitudes and phases of the distortion terms are shown to be important in determining the errors and their maximum values. Exact simulations confirm the accuracy and predictions of the first-order analysis. Under an assumed power-law relation between σhv and the biomass, the system distortions and noise are converted into biomass estimation errors, and it is shown that the magnitude of the deviation of the channel imbalance from unity must be 4–5 dB less than the crosstalk, or it will dominate the error in the biomass. For uncalibrated data and midrange values of biomass, the crosstalk must be less than ?24 dB if the maximum possible error in the biomass is to be within 20% of its true value. A less stringent condition applies if the amplitudes and phases of the distortion terms are considered random since errors near the maximum possible are very unlikely. For lower values of the biomass, the noise becomes increasingly important because the σhv signal-to-noise ratio is smaller.
关键词： Biomass,Faraday rotation,polarimetric measurements,system distortion,calibration,long-wavelength radar
更新于2025-09-23 15:19:57
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Disparities selection controlled by the compensated image quality for a given bitrate
摘要： A stereoscopic image consists of two views rendering a depth sense. Indeed each eye is constrained to look at one view, and the small objects displacements across the two views are interpreted as an indication of depth. These displacements are exploited as speci?c inter-view redundancies from a compression viewpoint. The classical still compression scheme, called disparity-compensated compression scheme, compresses one view independently of the second view, and a block-based disparity map modeling the displacements is losslessly compressed. The difference between the original view and its disparity predicted view is then compressed and used by the decoder to compute the compensated view to improve the disparity predicted view. However, a proof of concept work has already shown that selecting disparities according to the compensated view, instead of the predicted view, yields increased rate-distortion performance. This paper derives from the JPEG-coder, a disparity-dependent analytic expression of the distortion induced by the compensated view. This expression is embedded into an algorithm with a reasonable numerical complexity approaching the performance obtained with the proof of concept work. The proposed algorithm, called fast disparity-compensated block matching algorithm, provides at the same bitrate an average performance increase as compared to the classical stereoscopic image coding schemes.
关键词： Stereoscopic image,Compression,Block matching algorithm,Disparity compensation,JPEG-distortion
更新于2025-09-23 15:19:57
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Numerical analysis of CdS-CIGS interface configuration on the performances of Cu(In,Ga)Se2 solar cells
摘要： One dimension solar Cell Simulation package (SCAPS) is used to analyze the impact of the CdS-CIGS interface configuration on the performances of CIGS solar cells. We simulated the current-voltage characteristic of two models of the cell: one with a donor type defect (OVC model) and the other with acceptor type defect (P+ model) at the CdS-CIGS interface. The advantages and disadvantages of these CIGS surface configuration on the electrical parameters were discussed according to their thicknesses, defect density and carrier lifetime. The simulation results show that the model with the P+ layer has poor performance when its thickness and defect density increase, due to a huge distortion on the J-V characteristic. On the other hand, the OVC layer plays a fundamental role in the performance of CIGS solar cells. Better performances are obtained with the OVC model when the density of donor defect is in the range 1013 - 1015 cm-3, the charge carriers lifetime in the range 0.02 - 1 ns, and the thickness of the OVC layer in the range 200 - 400 nm.
关键词： P+ layer,OVC layer,SCAPS-1D,Distortion,CdS-CIGS interface
更新于2025-09-23 15:19:57
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Curvature-Induced Twist in Homeotropic Nematic Tori
摘要： We confine a nematic liquid crystal with homeotropic anchoring to stable toroidal droplets and study how geometry affects the equilibrium director configuration. In contrast to the case of cylindrical confinement, we find that the equilibrium state is chiral—a twisted and escaped radial director configuration. Furthermore, we find that the magnitude of the twist distortion increases as the ratio of the ring radius to the tube radius decreases; we confirm this with computer simulations of optically polarized microscopy textures. In addition, numerical calculations also indicate that the local geometry indeed affects the magnitude of the twist distortion. We further confirm this curvature-induced twisting using bent cylindrical capillaries.
关键词： twist distortion,nematic liquid crystal,curvature-induced twisting,chiral,toroidal droplets,homeotropic anchoring
更新于2025-09-23 15:19:57
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Propensity for spontaneous relaxor-ferroelectric transition in quenched (Na <sub/>1/2</sub> Bi <sub/>1/2</sub> )TiO <sub/>3</sub> -BaTiO <sub/>3</sub> compositions
摘要： Recently, quenching lead-free non-ergodic relaxor Na1/2Bi1/2TiO3-BaTiO3 (NBT-BT) materials has been reported to increase the thermal depolarization temperature and enhance the lattice distortion. Driven by the conjecture that enhanced lattice distortion is typically associated with the onset of ferroelectric order, two non-ergodic relaxor NBT-BT compositions at the morphotropic phase boundary were investigated. As evident from the temperature-dependent permittivity, both compositions exhibit a stabilization of ferroelectric order upon quenching. An increase in the depolarization temperature by 40–60 °C is observed. Moreover, the composition with higher tetragonality undergoes a spontaneous relaxor-ferroelectric transition upon quenching. Annealing in oxygen atmosphere is shown to revert back the quenching-induced ferroelectric order to the relaxor state.
关键词： relaxor-ferroelectric transition,NBT-BT,quenching,lattice distortion,depolarization temperature
更新于2025-09-23 15:19:57
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[IEEE OCEANS 2018 MTS/IEEE Charleston - Charleston, SC, USA (2018.10.22-2018.10.25)] OCEANS 2018 MTS/IEEE Charleston - Geometric Distortion Correction for the Underwater Images
摘要： Non-metric cameras have been widely used in applications of obtaining geometric information of the underwater objects using either digital photogrammetric approaches or computer vision algorithms. All the underwater images exhibit significant geometric distortions caused by lens distortions and light refraction in underwater imaging, which must be geometrically corrected. In this paper, a geometric distortion correction method for the underwater images is proposed, which uses the sets of distortion parameters obtained through the iterative camera calibration to determine the position relationship between the original images and the final corrected images, and then the gray values of the final corrected images are directly resampled from the original images. The GoPro Hero 5 Black calibration results show that the final accuracies are close to 0 pixel after three iterations; all the final distortion parameters calculated with the iterative calibration method are decreased after several iterations and can be ignored. By contrast, the original image was corrected well with the three sets of distortion parameters calculated with the iterative calibration method. An example shows that the successful generation of point clouds illustrates the effectiveness of the geometric correction. The proposed correcting method provides a technique not only to greatly reduce the distortion through applying a series of distortion parameters but also preserve the image quality through a smart resampling way.
关键词： sets of distortion parameters,once resampling,iterative camera calibration,underwater images,geometric correction
更新于2025-09-19 17:15:36
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[IEEE 2018 Ural Symposium on Biomedical Engineering, Radioelectronics and Information Technology (USBEREIT) - Yekaterinburg (2018.5.7-2018.5.8)] 2018 Ural Symposium on Biomedical Engineering, Radioelectronics and Information Technology (USBEREIT) - The influence of load variations on the of autodyne response formation in microwave oscillators under strong reflected emission
摘要： On the basis of the developed mathematical model of interaction of the single-circuit microwave oscillator with a strong reflected emission, using numerical methods, the role of load variations on the process of forming the autodyne response is shown. The coefficients of harmonics are calculated as well as amplitudes of harmonic components of the spectrum and levels of average values of load changes depending on a magnitude of the reflection coefficient modulus and changes of its phase. It is established that the main cause of distortions of the autodyne response under the strong reflected emission is the load 'non-linearity'. In the case of a weak signal, when the modulus of the reflection coefficient is much lower than one, the load changes are almost harmonic ones and the determinative role in formation of signals with distortions belongs to processes associated with the irregularity of the reflected emission phase incursion.
关键词： autodyne,autodyne response,signal distortion,microwave oscillator,strong reflected emission
更新于2025-09-19 17:15:36
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Division model-based distortion correction method for head-mounted displays
摘要： In this paper, we present a simple and efficient method for correcting the asymmetric and nonlinear geometrical distortion of a head‐mounted display (HMD). The method divides the object space into a number of quadratic triangular elements and applies a quadratic predistortion for each image section so that it can handle the distortion with any complex shapes caused by the decentering and tilted optics and improve the calibration accuracy. The errors introduced in the process of fabricating and assembling can also be eliminated. We investigated the use of a quadratic division model and two types of linear division models on an off‐axis HMD to correct the optical distortion. Experimental results demonstrated that the quadratic division model converged at a faster rate and produced higher accuracy over the typical linear model. The average root of mean square error (RMSE) after distortion correction was one pixel, and the maximum standard deviations in all rows and columns were 0.67 pixel and 0.57 pixel. In addition, the deformation continuity is maintained by using the quadratic element with connected midside nodes.
关键词： distortion correction,head‐mounted display (HMD),quadratic element,division model
更新于2025-09-19 17:15:36